This multicenter, randomized, double blind trial of Zidovudine (ZDV) versus 2'3' Dideoxinosine (ddI) versus a combination of ZDV and ddI evaluated safety, tolerance, and efficacy. Eight-hundred nineteen children between the ages of 3 months to 17 years were enrolled in the study. Treatment continued for 104 weeks. Clinical and lab evaluations were performed at specific intervals. Primary endpoints were survival and disease progression. Secondary endpoints were clinical, immunology, virologic and drug associated toxicity or intolerance parameters. Patients who were on AZT alone did poorly compared to patients on ddI alone or AZT and ddI.